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|
//! Window, GL context, and the caller-driven frame loop.
//!
//! The C ABI is pull-style: the caller owns the loop and calls
//! [`App::begin_frame`] / [`App::end_frame`] around its own widget calls.
//! `eframe` inverts that — it owns the loop and calls the app — so this backend
//! drives `winit` with `pump_app_events` and paints through `egui_glow`,
//! keeping the ABI (and every consumer of it) unchanged.
//!
//! One thing does **not** get to move outside the event loop: the present.
//! Wayland gives a surface one buffer per frame callback, and winit tracks
//! those callbacks itself. Presenting from outside its `RedrawRequested`
//! dispatch desynchronizes that bookkeeping — the compositor stops calling
//! back, the next `swap_buffers` blocks inside EGL with the session waiting on
//! it, and the whole desktop stalls for seconds. So [`App::end_frame`] hands
//! the finished frame to [`Handler`] and pumps until it is painted from inside
//! the callback, which is also what paces the caller's loop.
use std::sync::Arc;
use std::time::{Duration, Instant};
use egui::ViewportId;
use glutin::config::{Config, ConfigTemplateBuilder};
use glutin::context::{ContextApi, ContextAttributesBuilder, PossiblyCurrentContext};
use glutin::display::GetGlDisplay as _;
use glutin::prelude::*;
use glutin::surface::{Surface, SurfaceAttributesBuilder, SwapInterval, WindowSurface};
use glutin_winit::{DisplayBuilder, GlWindow as _};
use vidya_core::Theme;
use winit::application::ApplicationHandler;
use winit::dpi::LogicalSize;
use winit::event::WindowEvent;
use winit::event_loop::{ActiveEventLoop, EventLoop};
use winit::platform::pump_events::EventLoopExtPumpEvents as _;
use winit::raw_window_handle::HasWindowHandle as _;
use winit::window::{Window, WindowId};
use crate::ui::Stack;
/// How long `vidya_open` waits for the platform to hand us a window.
const OPEN_TIMEOUT: Duration = Duration::from_secs(5);
/// How long a finished frame waits for a frame callback before being dropped.
/// A window nobody is compositing (minimized, on another workspace) simply
/// stops presenting; the caller's loop keeps running.
const PRESENT_TIMEOUT: Duration = Duration::from_millis(250);
/// Pacing floor, so a caller that never sets a target FPS still yields.
const DEFAULT_FRAME_BUDGET: Duration = Duration::from_micros(16_666);
/// Build the event loop, preferring X11 where both backends exist.
///
/// Native Wayland does not survive this ABI's shape: the caller owns the loop,
/// so winit is driven with `pump_app_events`, and a surface driven that way
/// stops receiving frame callbacks after its first commit — the window never
/// gets a second frame and the session stalls behind it. Under X11 (XWayland
/// included) presentation does not depend on those callbacks, and the same loop
/// runs at full frame rate. Falls back to the default backend when X11 is
/// unavailable, so a compositor without XWayland still gets a window.
#[cfg(all(unix, not(target_os = "macos"), not(target_os = "android")))]
fn build_event_loop() -> Result<EventLoop<()>, String> {
use winit::platform::x11::EventLoopBuilderExtX11 as _;
if let Ok(el) = EventLoop::builder().with_x11().build() {
return Ok(el);
}
eprintln!("vidya: X11 unavailable; falling back to Wayland (expect stalls)");
EventLoop::builder()
.build()
.map_err(|e| format!("event loop: {e}"))
}
/// Android has no display connection to choose: the activity already owns one,
/// and winit reaches it through the handle the glue was started with. Without
/// that handle there is no event loop to build at all, which is why
/// `libvidya.so` is the NativeActivity's own library — see `android.rs`.
#[cfg(target_os = "android")]
fn build_event_loop() -> Result<EventLoop<()>, String> {
use winit::platform::android::EventLoopBuilderExtAndroid as _;
let app = crate::android::android_app()
.ok_or_else(|| "no AndroidApp: vidya_open ran outside android_main".to_owned())?;
EventLoop::builder()
.with_android_app(app)
.build()
.map_err(|e| format!("event loop: {e}"))
}
#[cfg(not(all(unix, not(target_os = "macos"))))]
fn build_event_loop() -> Result<EventLoop<()>, String> {
EventLoop::builder()
.build()
.map_err(|e| format!("event loop: {e}"))
}
/// Window, GL surface, painter, and egui input translation.
///
/// Created on the first `resumed`, the only point where winit guarantees a
/// usable display connection on every platform.
///
/// The surface is the one part that does not live as long as the rest. Android
/// takes the native window away whenever the activity leaves the foreground and
/// hands back a *new* one on the way in, so a surface built on the old one
/// presents to nothing — a black window, with `swap_buffers` reporting nothing
/// wrong. It is dropped on `suspended` and rebuilt on the next `resumed`; the
/// context and its textures outlive both, which is why the app comes back with
/// its fonts and images intact rather than reloading them.
struct Gl {
window: Window,
/// `None` between `suspended` and the `resumed` that follows it.
surface: Option<Surface<WindowSurface>>,
/// Kept for that rebuild: a surface has to match the config its context
/// was created against.
config: Config,
context: PossiblyCurrentContext,
painter: egui_glow::Painter,
winit_state: egui_winit::State,
}
impl Gl {
fn create(
el: &ActiveEventLoop,
egui_ctx: &egui::Context,
title: &str,
width: u32,
height: u32,
) -> Result<Self, String> {
let attrs = Window::default_attributes()
.with_title(title)
.with_inner_size(LogicalSize::new(width as f64, height as f64));
let (window, config) = DisplayBuilder::new()
.with_window_attributes(Some(attrs))
.build(
el,
ConfigTemplateBuilder::new().with_alpha_size(0),
// egui does its own anti-aliasing; this just avoids picking a
// degenerate config.
|configs| {
configs
.reduce(|best, c| {
if c.num_samples() > best.num_samples() {
c
} else {
best
}
})
.expect("no GL config")
},
)
.map_err(|e| format!("GL display: {e}"))?;
let window = window.ok_or_else(|| "no window was created".to_owned())?;
let raw = window
.window_handle()
.map_err(|e| format!("window handle: {e}"))?
.as_raw();
let display = config.display();
// Desktop GL first, GLES second — the order eframe uses.
let context = unsafe {
display
.create_context(&config, &ContextAttributesBuilder::new().build(Some(raw)))
.or_else(|_| {
display.create_context(
&config,
&ContextAttributesBuilder::new()
.with_context_api(ContextApi::Gles(None))
.build(Some(raw)),
)
})
.map_err(|e| format!("GL context: {e}"))?
};
let surface = build_surface(&window, &config)?;
let context = context
.make_current(&surface)
.map_err(|e| format!("make current: {e}"))?;
set_vsync(&surface, &context);
let glow_ctx = unsafe {
glow::Context::from_loader_function_cstr(|s| display.get_proc_address(s).cast())
};
let painter = egui_glow::Painter::new(Arc::new(glow_ctx), "", None, false)
.map_err(|e| format!("painter: {e}"))?;
let winit_state = egui_winit::State::new(
egui_ctx.clone(),
ViewportId::ROOT,
&window,
None,
window.theme(),
Some(painter.max_texture_side()),
);
Ok(Self {
window,
surface: Some(surface),
config,
context,
painter,
winit_state,
})
}
/// Give up the surface the platform is about to invalidate. The context is
/// released from this thread first: destroying a surface that is still
/// current is not something EGL owes an answer for.
fn suspend(&mut self) {
if self.surface.is_none() {
return;
}
if let Err(e) = self.context.make_not_current_in_place() {
eprintln!("vidya: releasing the GL context failed: {e}");
}
self.surface = None;
}
/// Build a surface on whatever native window the platform has now, and make
/// the context current on it again. A failure here leaves the surface
/// `None`, so the loop keeps running and drops frames rather than painting
/// into a surface that is not there.
fn resume(&mut self) {
if self.surface.is_some() {
return;
}
let surface = match build_surface(&self.window, &self.config) {
Ok(surface) => surface,
Err(e) => {
eprintln!("vidya: rebuilding the GL surface failed: {e}");
return;
}
};
if let Err(e) = self.context.make_current(&surface) {
eprintln!("vidya: make current failed on resume: {e}");
return;
}
set_vsync(&surface, &self.context);
// The new window is rarely the old one's size — a keyboard may have
// gone away under it, or the device turned.
self.window.request_redraw();
self.surface = Some(surface);
}
}
fn build_surface(window: &Window, config: &Config) -> Result<Surface<WindowSurface>, String> {
let attrs = window
.build_surface_attributes(SurfaceAttributesBuilder::new())
.map_err(|e| format!("surface attributes: {e}"))?;
// SAFETY: the attributes name this window, which outlives the surface.
unsafe {
config
.display()
.create_window_surface(config, &attrs)
.map_err(|e| format!("GL surface: {e}"))
}
}
fn set_vsync(surface: &Surface<WindowSurface>, context: &PossiblyCurrentContext) {
if let Err(e) = surface.set_swap_interval(
context,
SwapInterval::Wait(std::num::NonZeroU32::new(1).expect("nonzero")),
) {
eprintln!("vidya: vsync unavailable ({e})");
}
}
/// A tessellated frame waiting for the compositor to ask for it.
struct PaintJob {
primitives: Vec<egui::ClippedPrimitive>,
textures_delta: egui::TexturesDelta,
pixels_per_point: f32,
clear: [f32; 4],
}
/// winit event sink. Owns everything that survives between frames.
struct Handler {
egui_ctx: egui::Context,
theme: Theme,
gl: Option<Gl>,
title: String,
width: u32,
height: u32,
should_close: bool,
/// Set when window creation fails, so `vidya_open` can report it.
error: Option<String>,
/// Whether the compositor is ready for another buffer. Starts open: the
/// initial configure entitles us to the first frame, and the frame callback
/// that arms every later one is only requested *by* presenting — waiting
/// for it before the first present deadlocks.
may_present: bool,
/// Whether the wait for the compositor already happened this frame.
///
/// `end_frame` waits unless it did. That matters because the wait is where
/// a drag's resizes arrive, and a caller that has already waited has also
/// already checked its layout against the result — pumping again between
/// that check and the present would let one more resize through, into the
/// gap the check just proved empty.
slot_waited: bool,
frames: u32,
/// The size, in pixels, the frame now being built laid itself out against.
///
/// A resize that lands *while* the caller walks its tree leaves the pass
/// measuring one size and the buffer another, and the strip between them
/// is painted with nothing but the clear colour — the charcoal band that
/// follows the edge being dragged. Comparing this with the window tells
/// the caller to walk the tree again before any of it is presented.
frame_dims: [u32; 2],
/// `VIDYA_CAPTURE=<path>`: dump one painted frame, then stop.
capture: Option<String>,
/// `VIDYA_RESIZE_AT` parsed: (frame, width, height), in frame order.
resize_at: Vec<(u32, f64, f64)>,
/// Which frame to dump. `VIDYA_CAPTURE_AT` moves it later than the third,
/// for a screen that only exists once something has loaded. `ms:2500` says
/// when rather than which — a window nobody is compositing skips frames, so
/// a frame number can be a wait with no end on an unfocused desktop.
capture_at: u32,
capture_after: Option<Duration>,
/// `VIDYA_CLICK_AT` parsed: (frame, x, y), in frame order.
click_at: Vec<(u32, f32, f32)>,
started: Instant,
}
impl Handler {
/// Paint and present. Only ever called from inside `RedrawRequested`.
fn present(&mut self, job: PaintJob) {
let Some(gl) = self.gl.as_mut() else {
return;
};
// Between a suspend and the resume after it there is nothing to present
// to. The caller's loop is unaffected; it just paints no frames.
let Some(surface) = gl.surface.as_ref() else {
return;
};
let size = gl.window.inner_size();
let dims = [size.width.max(1), size.height.max(1)];
gl.painter.clear(dims, job.clear);
gl.painter.paint_and_update_textures(
dims,
job.pixels_per_point,
&job.primitives,
&job.textures_delta,
);
self.frames += 1;
// Third frame: fonts and layout have settled by then.
// A click the desktop never sent: `VIDYA_CLICK_AT=frame:x,y` presses and
// releases the left button at a point, so an interaction can be tested
// where there is nobody to do the clicking.
for &(at, x, y) in &self.click_at {
if self.frames == at {
let pos = egui::pos2(x, y);
let events = &mut gl.winit_state.egui_input_mut().events;
events.push(egui::Event::PointerMoved(pos));
for pressed in [true, false] {
events.push(egui::Event::PointerButton {
pos,
button: egui::PointerButton::Primary,
pressed,
modifiers: egui::Modifiers::default(),
});
}
}
}
let due = match self.capture_after {
Some(after) => self.started.elapsed() >= after,
None => self.frames == self.capture_at,
};
if due {
if let Some(path) = self.capture.take() {
capture_frame(gl, dims, &path);
}
}
// Order matters. `pre_present_notify` lets winit attach its frame
// callback to the commit that `swap_buffers` is about to make, and the
// redraw request that arms the *next* callback only counts once that
// commit has happened.
gl.window.pre_present_notify();
if let Err(e) = surface.swap_buffers(&gl.context) {
eprintln!("vidya: swap_buffers failed: {e}");
}
gl.window.request_redraw();
}
}
/// Put a Ctrl/Cmd+V back into egui's input when it dropped the keystroke.
///
/// egui-winit answers a paste shortcut by reading the clipboard's *text* and
/// pushing an `Event::Paste` with it — and returns there, pushing nothing at
/// all when the clipboard holds no text. A copied picture is exactly that
/// case, so the one gesture that means "paste this picture" was the one
/// gesture egui never heard about.
///
/// The key event it would have pushed goes back in. Nothing in egui acts on a
/// bare Ctrl+V — a text field pastes from `Event::Paste` — so this is inert
/// except to a caller that goes looking for it, which is what `:entry`'s
/// `paste-empty` does.
fn note_paste_shortcut(gl: &mut Gl, event: &WindowEvent) {
let WindowEvent::KeyboardInput { event: key, .. } = event else {
return;
};
if !key.state.is_pressed() {
return;
}
let modifiers = gl.winit_state.egui_input().modifiers;
if !modifiers.command {
return;
}
// Logical first, physical as the fallback: the same rule egui-winit uses,
// so a layout with no Latin V of its own still pastes from where V sits.
let logical_v = matches!(
&key.logical_key,
winit::keyboard::Key::Character(c) if c.eq_ignore_ascii_case("v")
);
let physical_v = matches!(
key.physical_key,
winit::keyboard::PhysicalKey::Code(winit::keyboard::KeyCode::KeyV)
);
if !logical_v && !physical_v {
return;
}
gl.winit_state
.egui_input_mut()
.events
.push(egui::Event::Key {
key: egui::Key::V,
physical_key: None,
pressed: true,
repeat: false,
modifiers,
});
}
impl ApplicationHandler for Handler {
fn resumed(&mut self, el: &ActiveEventLoop) {
if let Some(gl) = self.gl.as_mut() {
// Not a first start: the activity came back to the foreground, and
// what it lost while it was away was the surface.
gl.resume();
// A window that stopped being composited stopped presenting too,
// and the redraw request that arms the next frame callback is only
// made *by* presenting. Nothing would ever ask for the first frame
// back without this.
self.may_present = true;
return;
}
match Gl::create(el, &self.egui_ctx, &self.title, self.width, self.height) {
Ok(gl) => {
vidya_core::apply(&self.egui_ctx, &self.theme);
self.gl = Some(gl);
}
Err(e) => {
self.error = Some(e);
self.should_close = true;
}
}
}
/// The platform is taking the native window away — Android does this every
/// time the activity leaves the foreground.
fn suspended(&mut self, _el: &ActiveEventLoop) {
if let Some(gl) = self.gl.as_mut() {
gl.suspend();
}
}
fn window_event(&mut self, _el: &ActiveEventLoop, _id: WindowId, event: WindowEvent) {
if let Some(gl) = self.gl.as_mut() {
// egui sees every event, including the ones handled below.
let _ = gl.winit_state.on_window_event(&gl.window, &event);
note_paste_shortcut(gl, &event);
if let WindowEvent::Resized(size) = event {
if size.width > 0 && size.height > 0 {
if let Some(surface) = gl.surface.as_ref() {
gl.window.resize_surface(surface, &gl.context);
}
}
}
}
match event {
WindowEvent::CloseRequested | WindowEvent::Destroyed => self.should_close = true,
WindowEvent::RedrawRequested => self.may_present = true,
_ => {}
}
}
}
/// One UI context per process, matching the ABI's window model.
pub struct App {
event_loop: EventLoop<()>,
handler: Handler,
/// Live only between `begin_frame` and `end_frame`.
pub stack: Stack,
frame_budget: Duration,
frame_started: Instant,
/// Frames skipped because nothing was compositing the window.
dropped: u32,
font_generation: u32,
}
impl App {
pub fn open(width: i32, height: i32, title: &str) -> Result<Self, String> {
let event_loop = build_event_loop()?;
let mut app = Self {
event_loop,
handler: Handler {
egui_ctx: egui::Context::default(),
theme: Theme::dark(),
gl: None,
title: title.to_owned(),
width: width.max(1) as u32,
height: height.max(1) as u32,
should_close: false,
error: None,
may_present: true,
slot_waited: false,
frames: 0,
frame_dims: [0, 0],
capture: std::env::var("VIDYA_CAPTURE").ok(),
resize_at: std::env::var("VIDYA_RESIZE_AT")
.unwrap_or_default()
.split(',')
.filter_map(|step| {
let (at, size) = step.split_once(':')?;
let (w, h) = size.split_once('x')?;
Some((at.parse().ok()?, w.parse().ok()?, h.parse().ok()?))
})
.collect(),
capture_at: std::env::var("VIDYA_CAPTURE_AT")
.ok()
.and_then(|v| v.parse().ok())
.unwrap_or(3),
click_at: std::env::var("VIDYA_CLICK_AT")
.unwrap_or_default()
.split(';')
.filter_map(|step| {
let (at, point) = step.split_once(':')?;
let (x, y) = point.split_once(',')?;
Some((at.parse().ok()?, x.parse().ok()?, y.parse().ok()?))
})
.collect(),
capture_after: std::env::var("VIDYA_CAPTURE_AT")
.ok()
.and_then(|v| v.strip_prefix("ms:").and_then(|ms| ms.parse().ok()))
.map(Duration::from_millis),
started: Instant::now(),
},
stack: Stack::default(),
frame_budget: DEFAULT_FRAME_BUDGET,
frame_started: Instant::now(),
dropped: 0,
font_generation: 0,
};
// Pump until the platform resumes us and the window exists.
let deadline = Instant::now() + OPEN_TIMEOUT;
while app.handler.gl.is_none() && app.handler.error.is_none() {
if Instant::now() > deadline {
return Err("timed out waiting for a window".to_owned());
}
app.pump(Duration::from_millis(10));
}
match app.handler.error.take() {
Some(e) => Err(e),
None => Ok(app),
}
}
fn pump(&mut self, timeout: Duration) {
self.event_loop
.pump_app_events(Some(timeout), &mut self.handler);
}
pub fn should_close(&mut self) -> bool {
self.pump(Duration::ZERO);
self.handler.should_close
}
pub fn theme(&self) -> &Theme {
&self.handler.theme
}
/// The innermost open node plus the live theme.
///
/// Returned together because widget calls need both, and they live in
/// different fields — splitting the borrow here keeps the call sites plain.
/// The window's size in points, as egui last saw it.
///
/// Points rather than pixels: a caller sizing something against this is
/// laying out, and layout is in the same units the widgets are. The
/// `width`/`height` the window was opened with are no answer — they are
/// what was asked for once, and say nothing about a window since dragged
/// wider.
///
/// egui keeps the last screen rect on its context, so this answers between
/// frames as well as during one. Zero before the first frame, which is the
/// honest answer to asking how big a window is before it has been painted.
pub fn screen_size(&self) -> (f32, f32) {
let rect = self.handler.egui_ctx.screen_rect();
if rect.width().is_finite() && rect.height().is_finite() {
(rect.width().max(0.0), rect.height().max(0.0))
} else {
(0.0, 0.0)
}
}
pub fn ui(&mut self) -> Option<(&mut egui::Ui, &Theme)> {
let theme = &self.handler.theme;
self.stack.top().map(|ui| (ui, theme))
}
pub fn set_mode(&mut self, mode: vidya_core::Mode) {
self.handler.theme = match mode {
vidya_core::Mode::Dark => Theme::dark(),
vidya_core::Mode::Light => Theme::light(),
};
vidya_core::apply(&self.handler.egui_ctx, &self.handler.theme);
}
pub fn set_target_fps(&mut self, fps: i32) {
self.frame_budget = match fps {
f if f > 0 => Duration::from_secs_f64(1.0 / f as f64),
_ => DEFAULT_FRAME_BUDGET,
};
}
/// Install a UI font as the highest-priority proportional family.
///
/// The symbol fallback installed by [`vidya_core::apply`] stays in place,
/// so punctuation and block art keep rendering.
pub fn load_font(&mut self, path: &str) -> bool {
let Ok(bytes) = std::fs::read(path) else {
return false;
};
self.font_generation += 1;
// Unique name per load: egui skips a name it already has.
let name = format!("vidya-ui-{}", self.font_generation);
self.handler
.egui_ctx
.add_font(egui::epaint::text::FontInsert::new(
&name,
egui::FontData::from_owned(bytes),
vec![egui::epaint::text::InsertFontFamily {
family: egui::FontFamily::Proportional,
priority: egui::epaint::text::FontPriority::Highest,
}],
));
true
}
/// Drain pending input and open an egui pass with a root [`egui::Ui`].
pub fn begin_frame(&mut self) {
self.pump(Duration::ZERO);
self.frame_started = Instant::now();
// Per-frame, and cleared here rather than after a present: a frame
// dropped because nobody was compositing never reaches one.
self.handler.slot_waited = false;
if self.handler.gl.is_none() || self.stack.is_active() {
// No window, or the caller skipped `vidya_end_frame`.
return;
}
let Some(gl) = self.handler.gl.as_mut() else {
return;
};
let input = gl.winit_state.take_egui_input(&gl.window);
// The size that input reports the window to be, kept for
// `resized_mid_frame` to compare the window against once the caller
// has finished walking its tree.
let size = gl.window.inner_size();
let dims = [size.width.max(1), size.height.max(1)];
// A resize the compositor never sent, for testing a layout that only
// goes wrong when the window changes size under it. `VIDYA_RESIZE_AT`
// is `frame:WIDTHxHEIGHT`, and asks winit for the size the way a drag
// of the window's edge would.
//
// Asked for here, after the input for this frame has been taken, so it
// lands where a drag actually lands it: in the middle of the walk,
// with the pass already measured against the old size. Requesting it
// from `present` instead would only ever resize between frames, which
// is the one case that was never a problem.
let building = self.handler.frames + 1;
for &(at, w, h) in &self.handler.resize_at {
if building == at {
let _ = gl
.window
.request_inner_size(winit::dpi::LogicalSize::new(w, h));
}
}
let ctx = &self.handler.egui_ctx;
ctx.begin_pass(input);
self.stack.push_root(ctx);
self.handler.frame_dims = dims;
}
/// Wait for the compositor to want a frame, dispatching events while we
/// wait — never inside `swap_buffers`, which would park the thread that
/// owes the compositor its replies and stall the session. This wait is
/// also what paces the caller's loop to the display.
///
/// Callable before the pass is closed as well as from `end_frame`, and the
/// second call is free. That is the point: the resizes a drag produces
/// arrive *in here*, so a caller that wants to know whether its layout is
/// still the right size has to wait first and ask afterwards. Asking
/// before the wait sees a window that has not been told to move yet.
pub fn await_present_slot(&mut self) {
let deadline = Instant::now() + PRESENT_TIMEOUT;
while !self.handler.may_present && Instant::now() < deadline {
self.pump(Duration::from_millis(2));
}
self.handler.slot_waited = true;
}
/// Whether the window changed size after this frame started laying out.
///
/// True means the pass now open measured a window that no longer exists,
/// and presenting it would paint a smaller layout into a larger buffer.
/// The caller answers by discarding the pass and walking the tree again;
/// the tree is retained and holds no sizes of its own, so a second walk is
/// simply the same tree laid out against the window as it now is.
pub fn resized_mid_frame(&mut self) -> bool {
if !self.stack.is_active() {
return false;
}
self.pump(Duration::ZERO);
let Some(gl) = self.handler.gl.as_ref() else {
return false;
};
let size = gl.window.inner_size();
[size.width.max(1), size.height.max(1)] != self.handler.frame_dims
}
/// Close the open pass and throw its output away, presenting nothing.
///
/// egui has to be told a pass ended whether or not anybody wants what it
/// produced — leaving one open would make the next `begin_pass` panic —
/// so this ends it and drops the result on the floor.
pub fn discard_frame(&mut self) {
if !self.stack.is_active() {
return;
}
self.stack.unwind();
let _ = self.handler.egui_ctx.end_pass();
}
/// Close the pass, then hand the frame to the event loop to present.
pub fn end_frame(&mut self) {
if !self.stack.is_active() {
return;
}
// Close anything the caller left open (a missing `vidya_card_end`).
self.stack.unwind();
if self.handler.gl.is_none() {
return;
}
let egui::FullOutput {
platform_output,
textures_delta,
shapes,
pixels_per_point,
..
} = self.handler.egui_ctx.end_pass();
let primitives = self.handler.egui_ctx.tessellate(shapes, pixels_per_point);
// Gamma, not linear: `Painter::clear` hands these straight to
// `glClearColor` against an sRGB framebuffer, so a `Rgba::from`
// conversion here would be applied twice and the window would clear to
// near-black instead of the palette's charcoal.
let clear = self
.handler
.theme
.palette
.window_bg
.to_normalized_gamma_f32();
if let Some(gl) = self.handler.gl.as_mut() {
gl.winit_state
.handle_platform_output(&gl.window, platform_output);
}
if !self.handler.slot_waited {
self.await_present_slot();
}
if self.handler.may_present {
self.handler.may_present = false;
self.handler.present(PaintJob {
primitives,
textures_delta,
pixels_per_point,
clear,
});
} else {
// Nobody is compositing this window (minimized, another workspace).
// Drop the frame rather than force a present that would block.
self.dropped += 1;
if self.dropped == 1 {
eprintln!("vidya: window is not being composited; dropping frames");
}
}
// Floor for platforms that do not throttle presents at all.
if let Some(left) = self.frame_budget.checked_sub(self.frame_started.elapsed()) {
std::thread::sleep(left);
}
}
}
impl Drop for App {
fn drop(&mut self) {
self.stack.unwind();
if let Some(gl) = self.handler.gl.as_mut() {
gl.painter.destroy();
}
}
}
/// Write the painted framebuffer to a binary PPM.
///
/// A rendering backend is otherwise unverifiable where the compositor refuses
/// screenshots, and in CI where there is nobody to look. Off unless
/// `VIDYA_CAPTURE` names a path.
fn capture_frame(gl: &Gl, dims: [u32; 2], path: &str) {
use glow::HasContext as _;
use std::io::Write as _;
let [w, h] = dims;
let mut rgba = vec![0u8; (w as usize) * (h as usize) * 4];
unsafe {
// Drain the pipeline: the pixels need not exist yet.
gl.painter.gl().finish();
gl.painter.gl().read_pixels(
0,
0,
w as i32,
h as i32,
glow::RGBA,
glow::UNSIGNED_BYTE,
glow::PixelPackData::Slice(Some(&mut rgba)),
);
}
let mut out = Vec::with_capacity((w as usize) * (h as usize) * 3 + 32);
out.extend_from_slice(format!("P6\n{w} {h}\n255\n").as_bytes());
// GL origin is bottom-left; PPM is top-down.
for row in (0..h as usize).rev() {
let start = row * w as usize * 4;
for px in rgba[start..start + w as usize * 4].chunks_exact(4) {
out.extend_from_slice(&px[..3]);
}
}
match std::fs::File::create(path).and_then(|mut f| f.write_all(&out)) {
Ok(()) => eprintln!("vidya: wrote {path}"),
Err(e) => eprintln!("vidya: capture failed: {e}"),
}
}
|